Due to the well documented health hazards of traditional tobacco cigarettes to smokers and bystanders, there has been a shift in the marketplace to find suitable alternatives for the delivery of nicotine to the lungs of a subject. Ideally, nicotine should be delivered to the subject's lungs without the creation of second hand smoke, and without the unpleasant odors associated with traditional tobacco smoking. One mechanism to achieve this is via inhalation of nicotine as a dry powder formulation. In such systems, a dry powder inhaler is used to deposit the powder on the inner surfaces of the lungs for absorption into the bloodstream. Unfortunately though, most dry powder inhalers have numerous undesirable features.
For example, many devices that utilize powder reservoirs have difficulty delivering properly metered doses, advancing the powder through the reservoirs as they are being emptied, and delivering the powder doses adequately to a user. Current powder delivery devices, including the Turbuhaler®, the Twisthaler®, and the NEXThaler, are also limited by ease of use and general design. The above mentioned devices require a user to hold the device upright to ensure proper dose delivery, and have the distinct profiles of prescription medication.
Current powder delivery devise are also incapable of delivering adequate powder doses at flow rates comparable to traditional tobacco smoking. Medical dry powder inhalers require high inspiratory flow rates, typically in the range of 60 liters/min (L/min) to 100 L/min or higher. A flow rate that is too low, such as in the range of 15 L/min or lower, would take too long of a draw for each dose to feel natural. Ideally, the flow rate should be in the range of 30 L/min to emulate traditional tobacco smoking.
One existing device is shown in U.S. Pat. No. 6,234,169 to Bulbrook (“Bulbrook”), which describes a cone shaped device that protrudes into a dry powder storage reservoir to generate a vortex-like effect inside the cone. The device uses the vortex to dip down inside the storage reservoir and pick up a slug of powder and deliver it to the airways of an individual. However, a significant limitation of the Bulbrook design is that it does not provide adequate energy inside the storage reservoir to deagglomerate the powder sufficiently to deliver the desired aerosol to the user. The Bulbrook design also lacks a reliable method of preventing accidental powder release or a feature for switching storage reservoirs.
Thus, there is a need in the art for a reservoir dry powder inhaler that can reliably meter a dry powder formulation independent of orientation and deliver a suitably deagglomerated dry powder for inhalation while maintaining ease of use in a discrete design. The present invention satisfies this need.